en.wikipedia.org/wiki/Standard_deviation

In statistics, the **standard deviation** is a measure that is used to quantify the
amount of variation or dispersion of a set of data values. A low **standard deviation**
...

www.mathsisfun.com/data/standard-deviation.html

The **Standard Deviation** is a measure of how spread out numbers are. Its symbol
is σ (the greek letter sigma). The formula is easy: it is the square root of the ...

www.khanacademy.org/math/probability/data-distributions-a1/summarizing-spread-distributions/a/calculating-standard-deviation-step-by-step

Interestingly, in the real world no statistician would ever calculate **standard**
**deviation** by hand. The calculations involved are somewhat complex, and the risk
of ...

www.calculator.net/standard-deviation-calculator.html

Free online tool to calculate the **standard deviation**, variance, mean, sum, and
confidence range for given numbers. Also find hundreds of other free online ...

www.robertniles.com/stats/stdev.shtml

A simpler explanation of **standard deviation**, written by a former math-major-
turned-journalist who likes to explain math to people don't understand or just
plain ...

www.investopedia.com/terms/s/standarddeviation.asp

**Standard deviation** is a measure of the dispersion of a set of data from its mean. It
is calculated as the square root of variance by determining the variation ...

mathworld.wolfram.com/StandardDeviation.html

Physical scientists often use the term root-mean-square as a synonym for
**standard deviation** when they refer to the square root of the mean squared
deviation of ...

www.statisticshowto.com/probability-and-statistics/standard-deviation

**Standard deviation** explained in plain English. How to find it by hand or using
technology. **Standard deviation** symbol. Step by step examples.